No LockUp on my 86 GN's 200r4

Brian Verson

Jun 19, 2001
Please someone Help Me . My transmission is working great except for no lock up . My scanner is telling the ECM is commanding it on but nothing happens any ideas .
Have you done the "braking test" to check its not working for sure? If working properly, you will feel it unlock then relock when tapping the brake at around 45 mph. If it's not working for sure, check for a good connection on the trans plug if you haven't already. It could a bad TCC solenoid, here is a detailed writeup on how to replace:

It's a simple job and a common repair with the 2004R.

another thing to check is the brake switch. There are two on top of each other. I think the top one is for the TCC lockup. Make sure that is contacting the brake pedal. Mine wasn't locking up because of that upper brake switch. I then adjusted it and got the lockup back. Good luck:)
I tried tapping the brake pedal at hwy speeds and there was no change in RPM on my tach . I took it to a friends shop that has a trans shifting unit called a Trans X 2000 . We hooked it up at the plug on the trans and bypassed the ECM . Still no lockup I replaced the converter when I rebuilt the trans . I rebuilt the trans because I had no lockup, when I got the converter out I found some worn out pieces and went ahead and rebuilt the trans and replaced the converter.

Should I have voltage at the plug on trans, how much & on what pins .

Measure voltage with the key on at terminal A on the vehicle harness. Should be 12V.

Next, measure the resistance between terminals A & D on the transmission case connector. It should be around 24 Ohms. This is checking the integrity of the internal harness and the condition of the solenoid coil.